This invention relates to a storage container for a liquid or granular solid.
It is often expedient to store liquids or flowable solids, particularly pulverulent or granular solids, in temporary storage containers. Thus, when a large scale fire occurs in a location remote from a mains water supply, for example, in the event of a forest fire, temporary storage may be required for water to be used in fighting the fire. Also in case of oil spillage in a river or in coastal waters, there may be a need to provide storage for oil and tarry residues that have been recovered from the spillage. In the event of famine emergencies, as in case of prolonged drought in remote regions, there may be a need to provide temporary storage for drinking water or for food, such as grain, for distribution to the local populace. In all such cases requirements for such a storage container are that it shall be collapsible, that it shall be readily portable, that it shall be easily transportable by air, that it shall be capable of swift assembly by possibly unskilled persons, and that it shall be safe in use.
An example of a suitable temporary storage container of this type is described in British Patent Specification No. 1586767 and Irish Patent Specification No. 49888. This describes a static tank or container for holding a fluent material and having a limp flexible bottom resting on a flat surface and form which upstands a limp flexible perimetral wall circular in plan. The container is maintained upstanding by flexible support means connected between the upper edge thereof and an upper horizontally disposed continuous member of a framework surrounding the perimetral wall. The perimetral wall is formed of waterproof-coated woven fabric of synthetic material with the warp of the fabric running lengthwise around the wall and the weft thereof being upright. The synthetic material has a strength to weight ratio and a stretch characteristic sufficient that the wall requires no internal reinforcement or external support against outward pressure from contents when filled into the tank or container. Five different forms of support are illustrated in FIG. 3 of British Patent Specification No. 1586767, U.S. Pat. No. 4,356,933 and of Irish Patent Specification No. 49888; three of these involve elastic straps, and one involves helical springs. The remaining type involves a resilient sheet looped around the upper horizontally disposed continuous member of the supporting framework between the junctions of two adjacent vertical rods forming part of the framework with the member, the opposed sides of the sheet being secured by adhesive or welding to the upper end of the perimetral wall.
Containers of this type in which the flexible support means comprises a plurality of elastic straps have been widely sold for use by aid agencies, by fire-fighting services, and by environmental protection services in many countries of the world. Such containers are available under the trade mark FASTANK(copyright) from Fast Engineering Limited of Old Mill Industrial Estate, Antrim, Northern Ireland BT41 4QE. The disassembled support structure and flexible container can be packed for transport and between periods of use in elongate boxes with carrying handles at each end which can easily be carried by two persons.
When such containers are used for storage of oils and tarry materials, for example, during clearing up operation after an oil spillage, there is a need after use to clean the tanks before they are packed away in readiness for re-use at another site. This is a time-consuming and somewhat tedious task because each of the flexible straps has to be disconnected from the container, cleaned separately and then re-assembled. In addition such containers comprise a multiplicity of parts, a factor which adds to its cost of manufacture. Some of the metal parts are curved or bent, a further factor which adds to the complexity of manufacture and the cost of the container.
It would be desirable to provide an improved form of storage container.
The present invention accordingly seeks to provide an improved portable storage container which is simpler in construction than prior art commercial forms of portable storage containers. It further seeks to provide an improved portable storage container having a flexible inner vessel which has a simpler form of suspension from an outer framework than commercial prior art portable storage containers. Another aim of the invention is to provide a portable storage container which is simpler to manufacture than prior art containers of this type. In addition the invention seeks to provide a storage container in which the use of curved or bent members can be substantially avoided, thereby simplifying both manufacture of such containers and also packing of such containers in storage boxes therefor. Still further it seeks to provide an improved portable storage container which can be quickly and more readily cleaned than existing commercial forms of portable storage containers, for example after use thereof for storage of oil or tarry residues.
According to the present invention there is provided a portable storage container comprising:
an exterior support frame defining an interior space having an upper periphery and including a plurality of upright members spaced from one another around the periphery of the interior space and a plurality of substantially horizontal elongate members disposed about the upper periphery of the interior space, the elongate members each extending along a corresponding side of a polygon;
a flexible vessel within the interior space having a bottom wall and an upstanding flexible perimetral wall secured to the bottom wall; and
elastic support means for the upper perimetral portion of the perimetral wall comprising a plurality of strips of elastic material, each of which extends over a corresponding elongate member of the supporting frame, a first end portion of each strip being bonded in a first region of bonding to an inner face of the perimetral wall, and a second end portion being bonded in a second region of bonding to an outer face of perimetral wall.
Each of said strips may include a first web portion extending freely from the upper rim of the flexible upstanding perimetral wall to the corresponding substantially horizontal elongate member, and a second web portion extending freely from the corresponding substantially horizontal member to the second region of bonding, the second web portion being longer than the first web portion. Thus the first web portion and the second web portion may subtend an included angle in a vertical plane of from about 15xc2x0 to about 30xc2x0. Preferably the second web portion is at least twice the length of the first web portion.
In one arrangement the bottom wall of the flexible vessel is substantially circular in plan.
The inner vessel can be provided with a plurality of tabs for facilitating flattening of the bottom wall in the empty condition of the inner vessel. If desired, each tab can be provided with an aperture for passage of a ground penetrating peg or for facilitating securement to one of the upright members.
In a preferred design the framework is substantially hexagonal in plan. According to an alternative design the framework is substantially octagonal in plan.
The first end portion preferably extends to a first arcuate concave edge of said strip and the second end portion extends to a second arcuate concave edge of said strip, the radius of curvature of the second concave edge being less than that of the first arcuate concave edge.
Conveniently the substantially horizontal elongate members comprise open ended members or male-ended members and the upright members are each provided with corresponding stub arms, each adapted to be snugly received within a corresponding open ended member or formed with a female socket for snug receipt of a corresponding male end of a male-ended member. In such a portable storage container the exterior support frame can further include a plurality of lower cross bars, each of which extends between an adjacent pair of upright members at a height of from about one quarter to about one half of the way up the height of the upright members. Typically such lower cross bars each extend between an adjacent pair of upright members at a height of about one third of the way up the height of the upright members. Conveniently the lower cross bars comprise open ended or male-ended members and in which the upright members are each provided with corresponding stub arms, each adapted to be snugly received within a corresponding open ended member or formed with a female socket for snug receipt of a corresponding male end of a male-ended member. The members forming the upper elongate members or the lower cross bars can be secured to corresponding stub arms by means of retaining pins, for example captive pins, adapted for reception in corresponding aligned bores in the stub arms and in the upper elongate members or cross bars. The open ended members can comprise hollow box section members.
The attachment of the second end portion of each strip to the outer face of the perimetral wall is preferably provided with reinforcement means, such as a separate gusset of flexible material folded into a V-shape, one arm of the V-shape being secured to the inner face of the strip and the other end being secured to the outer face of the perimetral wall.
The flexible perimetral wall has an upper rim and, in one arrangement comprises a lower perimetral portion secured to the bottom wall and extending up from the bottom, a medial perimetral portion above the lower perimetral portion, and an upper perimetral portion above the medial perimetral portion, the upper perimetral portion extending less than one quarter of the height of the perimetral wall down from the upper rim of the perimetral wall, while the lower perimetral portion extending no more than one quarter of the height of the perimetral wall up from the bottom wall. In this case the end of each strip that is bonded to the inner face of the perimetral wall is bonded to the upper perimetral portion thereof, while the other end of that strip is bonded to the outer face of the perimetral wall on the medial perimetral portion thereof.